Hi. I know that hydrogen peroxide undergoes spontaneous decomposition when dissolved in an acqueous solution. According to some literature I found, H2O2 would have a half-life of ~5-10 hrs, however I cannot find exact analytical determinations, nor can I find how temperature affects spontaneous H2O2 breakdown. For example, what is the expected hydrogen peroxide half-life at 37 °C, pH 7?
Does anyone have precise informations on the argument?
Thank You very much in advance
Stefano Falone
Dept. of Life, Health and Environmental Sciences, University of L'Aquila - Italy
Hi
the rate of decomposition of hydrogen peroxide is strongly dependent on the amount of metal impurities in your solvent/buffer (Fenton reaction). Hence one cannot give you a precise rate. The more metal cation, the fastest the decompostion is. In bottles, there are always some chelatants to help conservation. Conversely, if you have extremely pure H2O2 you can keep it for months.
In conclusion, you must measure YOUR rate in your conditions with your buffer, if any! If you don't want to use liters of water you can pepare a bulk solution and take samples every (e.g.) hours and measure the concentration by the iodine method, which is very precise.
This contribution could be interesting for you:
https://www.researchgate.net/publication/234110563_Factors_Affecting_Decomposition_of_Hydrogen_Peroxide
Cheers, Christian
Conference Paper Factors Affecting Decomposition of Hydrogen Peroxide
Interesting work, Christian. Unfortunately, the paper does not include my specific experimental conditions (pH 7 and 37 °C). However, I can see that T strongly affects H2O2 decomposition rate. Not exactly what I was looking for, but undoubtedly useful for my discussion.
Thanks a lot.
Stefano
Do you have a UV spectrophotometer available?
You can determine the decomposition rate of hydrogen peroxide at the desired conditions by monitoring the absorbance at 240 nm (against appropriated blank). Then, you can used molar attenuation coefficient 0.04 mM-1cm-1 (Aebi, 1984) to calculate the H2O2 concentration over time.
Yes, I may use my UV spectrophotometer. However, in order to avoid to have my spectrophotometer working for days, I was trying to find some existing literature. In fact, my spectrophotometer uses a water-based system to maintain a constant temperature, therefore my readings would require hundreds of liters of tap water.
Thank You very much for Your very kind response
Stefano
Hi
the rate of decomposition of hydrogen peroxide is strongly dependent on the amount of metal impurities in your solvent/buffer (Fenton reaction). Hence one cannot give you a precise rate. The more metal cation, the fastest the decompostion is. In bottles, there are always some chelatants to help conservation. Conversely, if you have extremely pure H2O2 you can keep it for months.
In conclusion, you must measure YOUR rate in your conditions with your buffer, if any! If you don't want to use liters of water you can pepare a bulk solution and take samples every (e.g.) hours and measure the concentration by the iodine method, which is very precise.
Thanks so much, Chantal. I guess Your suggestion may be of great help.
Best regards
Stefano
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